.header{
    position: relative;
    margin-top: 30px;
    width: 100%;
    height: 288px;
    overflow: hidden;
    /* margin-bottom: 10px; */
}
.img{
    position: absolute;
    clear: both;
    width: 100%;
    height: 100%;
    background: transparent;
    transition: 0.2s;
}
.btnL{
    /* position: relative; */
    opacity: 0.7;
    /* top:-300px; */
    /* left:0; */
    width: 100px;
    height: 300px;
    z-index: 4;
    background: -webkit-linear-gradient(left,#9e9e9e, transparent); /* Safari 5.1 - 6.0 */
    background: -o-linear-gradient(right,#9e9e9e, transparent); /* Opera 11.1 - 12.0 */
    background: -moz-linear-gradient(right,#9e9e9e, transparent); /* Firefox 3.6 - 15 */
    background: linear-gradient(to right,#9e9e9e, transparent); /* 标准的语法 */
}
.btnR{
    /* position: relative; */
    opacity: 0.7;
    /* top:-300px; */
    /* left: 1300px; */
    width: 100px;
    height: 300px;
    z-index: 4;
    background: -webkit-linear-gradient(left,transparent,#9e9e9e ); /* Safari 5.1 - 6.0 */
    background: -o-linear-gradient(right,transparent, #9e9e9e); /* Opera 11.1 - 12.0 */
    background: -moz-linear-gradient(right,transparent, #9e9e9e); /* Firefox 3.6 - 15 */
    background: linear-gradient(to right,transparent, #9e9e9e); /* 标准的语法 */
}
.buttons{
    display: flex;
    flex-direction: row;
    justify-content: space-between;
}